4,5-Diamino-2,6-dimercaptopyrimidine as a spectrophotometric reagent for the determination of selenium in semiconductors and animal feeds

The Analyst ◽  
1981 ◽  
Vol 106 (1263) ◽  
pp. 720-723 ◽  
Author(s):  
A. Izquierdo ◽  
M. D. Prat ◽  
L. Aragonés
Keyword(s):  
Animal Feeds

scholarly journals Comparisons of Karl Fischer Method with Oven Methods for Determination of Water in Forages and Animal Feeds

1999 ◽  
Vol 82 (4) ◽  
pp. 799-808 ◽  
Author(s):  
Nancy Thiex ◽  
Terri Van Erem
Keyword(s):  
Standard Error ◽  
Near Infrared ◽  
Corn Silage ◽  
Infrared Reflectance ◽  
Near Infrared Reflectance ◽  
Karl Fischer ◽  
Animal Feeds ◽  
Karl Fischer Method ◽  
Fischer Method

Abstract In a comparative study of the Karl Fischer method with oven methods for determination of water in forages and animal feeds, oven methods yielded the following relative recoveries (expressed as a percentage of the recovery obtained by the Karl Fischer method) for hay, haylage, and corn silage, respectively: (1) drying at 135°C for 2 h (AOAC 930.15), 113,162, and 133%; (2) drying at 104°C for 3 h (AOAC 935.29), 96,122, and 113%; and (3) drying at 104°C for 6 h, 97, 129, and 117%. Relative recoveries for nonurea-containing and urea-containing feed, respectively, were as fol lows: (1) drying at 135°C for 2 h (AOAC 930.15), 116 and 2746% (2) drying at 104°C for 3 h (AOAC 935.29), 88 and 239%; (3) drying at 95°C for 5 h under vacuum (AOAC 934.01), 83 and 727% (4) drying at 104°C for 6 h, 90 and 427%; and (5) drying at 110°C for 3 h, 94 and 425%. Preliminary near-infrared reflectance calibrations for water (moisture) based on the Karl Fischer method were promising (r2 = 0.98; standard error of calibration = 0.20).

Quantitative Thin Layer Chromatographic Determination of Furazolidone and Nitrofurazone in Animal Feeds

1978 ◽  
Vol 61 (1) ◽  
pp. 92-95
Author(s):  
Ugo R Cieri
Keyword(s):  
Thin Layer ◽  
Ultraviolet Light ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Animal Feeds ◽  
Recording Spectrophotometer ◽  
Tungsten Lamp

Abstract A method is presented for determining the nitrofurans furazolidone and nitrofurazone in animal feeds. The sample is extracted with acetone, and aliquots of the concentrated extract are spotted on thin layer chromatographic fluorescent plates. After development in CHCl3-methanol (90+10), the bands containing the nitrofurans are detected under shortwave ultraviolet light, scraped from the plate, and extracted with ethanol. The centrifuged extracts are scanned from 500 to 300 nm on a recording spectrophotometer with a tungsten lamp, and the absorbance maxima near 360 nm are used for quantitation. To compensate for extraction and chromatographic losses and for other interferences, the nitrofuran not present in the sample is added as an internal standard. The method is generally not applicable at a level below 0.005% since detection of the bands becomes difficult.

Rapid Thin Layer Chromatographic Method for Determination of Zearalenone and Zearalenol in Grains and Animal Feeds

1984 ◽  
Vol 67 (3) ◽  
pp. 580-582 ◽  
Author(s):  
Steven P Swanson ◽  
Richard A Corley ◽  
Donald G White ◽  
William B Buck
Keyword(s):  
Thin Layer ◽  
Ethyl Acetate ◽  
Salt Solution ◽  
Lead Acetate ◽  
High Performance ◽  
Chromatographic Method ◽  
Inexpensive Method ◽  
Animal Feeds ◽  
Better Than

Abstract A rapid and inexpensive method has been developed for the analysis of zearalenone and zearalenol in grains and animal feeds. The method involves extraction with 75% methanol, precipitation of pigments with lead acetate, and defatting with petroleum ether. The mycotoxins are subsequently partitioned into toluene–ethyl acetate, chromatographed on high performance thin layer chromatographic plates, and detected after treatment with Fast Violet B salt solution. Sensitivity of the method is better than 80 ng/g for zearalenone and 200 ng/g for zearalenol. Ten samples can be completed in less than 2 h. The method is applicable for zearalenone in corn, wheat, barley, millet, and swine feeds.

Determination of Polybrominated Biphenyl Residues in Dry Animal Feeds

1975 ◽  
Vol 58 (6) ◽  
pp. 1206-1210
Author(s):  
Norbert V Fehringer
Keyword(s):  
Petroleum Ether ◽  
Pesticide Residues ◽  
Methylene Chloride ◽  
Chromatographic Column ◽  
Animal Feeds ◽  
Polybrominated Biphenyls ◽  
Polybrominated Biphenyl ◽  
Liquid Chromatographic

Abstract A new procedure is described for the determination of polybrominated biphenyls (PBBs) in dry animal feeds and developmental results are discussed. Finely ground feed is packed into a chromatographic column containing Celite and then eluted with methylene chloride. The concentrated extract is cleaned up by elution with petroleum ether through Florisil before gas-liquid chromatographic quantitation. Chromatograms thus obtained were essentially free of the interfering peaks encountered when using AOAC methods for pesticide residues in dry products. Results of feed analyses by the proposed procedure averaged 30% higher than those obtained by AOAC procedures. Recoveries of PBBs from samples fortified at levels of 0.04 to 0.4 ppm ranged from 90 to 104%, with an average of 98%.

scholarly journals Determination of Starch, Including Maltooligosaccharides, in Animal Feeds: Comparison of Methods and a Method Recommended for AOAC Collaborative Study

2009 ◽  
Vol 92 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Mary B Hall
Keyword(s):  
Dry Matter ◽  
Collaborative Study ◽  
Ease Of Use ◽  
Acetate Buffer ◽  
Sample Handling ◽  
Animal Feeds ◽  
Heat Stable ◽  
Replacement Method ◽  
Aoac Method

Abstract Starch is a nutritionally important carbohydrate in feeds that is increasingly measured and used for formulation of animal diets. Discontinued production of the enzyme Rhozyme-S required for AOAC Method 920.40 invalidated this method for starch in animal feeds. The objective of this study was to compare methods for the determination of starch as potential candidates as a replacement method and for an AOAC collaborative study. Many starch methods are available, but they vary in accuracy, replicability, and ease of use. After assays were evaluated that differed in gelatinization method, number of reagents, and sample handling, and after assays with known methodological defects were excluded, 3 enzymaticcolorimetric assays were selected for comparison. The assays all used 2-stage, heat-stable, -amylase and amyloglucosidase hydrolyses, but they differed in the gelatinization solution (heating in water, 3-(N-morpholino) propanesulfonic acid buffer, or acetate buffer). The measured values included both starch and maltooligosaccharides. The acetate buffer-only method was performed in sealable vessels with dilution by weight; it gave greater starch values (26 percentage units of sample dry matter) in the analysis of feed/food substrates than did the other methods. This method is a viable candidate for a collaborative study.

scholarly journals Determination of Decoquinate in Animal Feeds by Liquid Chromatography: Collaborative Study

2008 ◽  
Vol 91 (4) ◽  
pp. 685-693 ◽  
Author(s):  
Anivis A Sanchez ◽  
Harold M Campbell ◽  
M S Ahmed ◽  
K Albert ◽  
C Applegate ◽  
...  
Keyword(s):  
Collaborative Study ◽  
The United States ◽  
Reversed Phase ◽  
Excitation Wavelength ◽  
Mechanical Agitation ◽  
Trace Level ◽  
Animal Feeds ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract The performance characteristics of a liquid chromatographic (LC) method for the analysis of decoquinate (DEC) in supplements, premixes, and complete animal feeds at medicating and trace levels were collaboratively studied. DEC is extracted from ground feed samples with 1 calcium chloridemethanol solution using mechanical agitation for 90 min. After centrifugation for 5 min and dilution (if necessary), an aliquot of the extract is diluted with water. The diluted extracts are filtered and analyzed by reversed-phase LC with fluorescence detection. Suspect positive trace-level samples are confirmed by using an alternate excitation wavelength. Fourteen test samples of medicated feeds, supplement, and medicated premix, along with 8 test samples for trace-level analysis, were sent to 13 collaborators (one in Canada, 4 in Europe, and 8 in the United States). Test samples were analyzed as blind duplicates. Acceptable results were received from 12 laboratories for the medicated test samples and from 13 laboratories for the trace-level samples. Repeatability relative standard deviation estimates ranged from 1.3 to 5.6. Reproducibility relative standard deviations estimates ranged from 2.8 to 6.1, and HorRat values ranged from 0.22 to 0.74.

CuSO4-TiO2 as Kjeldahl Digestion Catalyst in Manual Determination of Crude Protein in Animal Feeds

1986 ◽  
Vol 69 (4) ◽  
pp. 664-666
Author(s):  
Peter F Kane
Keyword(s):  
Standard Deviation ◽  
Crude Protein ◽  
T Test ◽  
Environmental Concerns ◽  
Animal Feeds ◽  
Significant Difference ◽  
Kjeldahl Digestion ◽  
Student’S T ◽  
Student’S T Test

Abstract The official AOAC manual Kjeldahl methods for determining crude protein in animal feeds have several disadvantages. For the HgO catalyst method, there are environmental concerns and a lengthy digestion. For the CuS04 catalyst method, the digestion period is shorter, but still 90 min. A different catalyst combination, CuS04-Ti02, makes 40 min digestion feasible. Comparison of these catalysts on a group of representative feeds resulted in a mean difference, Cu-Ti minus HgO, of 0.034% protein. Standard deviation of the differences was 0.36. A Student’s t-test showed no significant difference. The method will be collaboratively studied.

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